1. Field of the invention
This invention relates to a sewing apparatus provided with a cassette mount to which a thread cassette is detachably attached and an informing control program for such a sewing apparatus.
2. Description of related art
Sewing apparatus have conventionally been provided including a cassette mount to which a thread cassette is detachably attached. The thread cassette accommodates a thread spool on which a thread is wound. The thread drawn from the thread cassette serves as a needle thread. The thread drawn from the thread cassette attached to the cassette mount is caused to extend between a pair of thread tension discs and then caught by a needle thread take-up lever. The thread is further caused to pass through a hole of a sewing needle mounted to a needle bar, thereby being set. The assignee of the present application filed a Japanese patent application to which application No. 2002-91558 has been assigned. This Japanese patent application discloses a sewing apparatus including a thread feeding mechanism operated in synchronization with attachment of the thread cassette to the cassette mount, and a threading mechanism. The thread drawn from the thread cassette is automatically passed through the needle hole by the thread feeding mechanism and threading mechanism.
In the foregoing sewing apparatus, the thread feeding mechanism includes a thread catching member and a moving mechanism for moving the thread catching member. Upon actuation of the thread feeding mechanism, the thread catching member is lowered so that the thread drawn from the thread cassette is caught by the thread catching member. The thread is carried near the needle hole and then tensioned in front of the needle hole. The threading mechanism comprises a threading shaft provided along the needle bar so as to be moved up and down and further rotated and a threading hook mounted on a lower end of the threading shaft so as to be allowed to pass through the needle hole. Upon actuation of the threading mechanism, the threading shaft is lowered to be positioned relative to the needle bar and then stopped. Successively, the threading shaft is rotated so that the threading hook is passed through the needle hole. The thread drawn from the thread cassette has been carried near the needle hole by the thread catching member. The thread is caught by the threading hook having been passed through the needle hole and subsequently, the threading shaft is rotated in the reverse direction so as to be pulled out of the needle hole.
In the sewing apparatus of the above-described type, the needle bar is moved up and down relative to an arm portion of the sewing apparatus by a needle bar vertically moving mechanism and is rocked right and left by a needle bar rocking mechanism. In this case, the needle bar and the threading mechanism are mounted on a needle bar frame pivotally mounted on a frame of the arm, so that the needle bar is stopped at any vertical position and at any zigzag position. On the other hand, the aforesaid thread feeding mechanism is mounted on the frame of the arm, and the thread drawn from the thread cassette is carried to a fixed position relative to the arm.
Accordingly, in order that a threading operation may be carried out desirably by the aforesaid threading mechanism and thread feeding mechanism, the needle bar, threading mechanism and thread feeding mechanism need to be in a proper positional relationship at the time of the threading operation or in other words, the needle bar needs to be located at a predetermined vertical position and a predetermined zigzag position. Furthermore, a pair of thread tension discs need to be in an open state when the sewing apparatus is constructed so that the thread drawn from the thread cassette is held between the thread tension discs in synchronization with attachment of the thread cassette to the cassette mount.
More specifically, the aforesaid sewing apparatus, wherein the thread is set in synchronization with attachment of the thread cassette to the cassette mount, has two conditions. In one condition, the thread cassette may be attached to the cassette mount and in the other condition, the thread cassette should not be attached to the cassette mount. However, the user has a difficulty in determining whether the thread cassette can be attached to the cassette mount, viewing a zigzag position of the needle bar or the like. Furthermore, the user could try to attach the thread cassette to the cassette mount without giving due consideration to whether the thread cassette can be attached. Accordingly, there is a possibility that the user may attach the thread cassette to the cassette mount although the sewing machine is in the condition where the thread cassette should not be attached. If the thread cassette should be attached in this condition, threading could not be carried out successfully by the threading mechanism since a vertical position or zigzag position of the needle bar relative to the thread feeding mechanism would be shifted or in the worst case, the threading mechanism would be damaged.
Furthermore, when the thread cassette is attached to the cassette mount with the paired thread tension discs being closed, the thread cannot be caught between the discs. As a result, the thread cannot be set properly. Alternatively, for example, when the sewing apparatus is provided with a sensor which needs to be checked in its initial state without the thread cassette being attached, the thread cassette is attached to the cassette mount before the sensor is checked, whereupon a failure may occur in the sewing apparatus.